Finned cooler of the solid block type for magnetrons



United States Patent Inventors Appl. No. Filed Patented Assignee Priority Yoshio Kato Mino;

Osamu Konosu, Otokuni-gun; Yoshio Nakagawa, F ushimi-kuQJapan 804,772

Mar. 6, 1969 Dec. 29, 1970 Matsushita Electronics Corporation Kadoma, Osaka-prefecture, Japan Mar. 8, 1968 Japan FINNED COOLER OF THE SOLID BLOCK TYPE FOR MAGNETRONS 3 Claims, 5 Drawing Figs.

U.S. Cl 313/46, 313/44, 313/45 Int. Cl HOlj 7/42, l-lOlj 19/74, l-lOlj 25/50 Field of Search 313/44, 45,

[56] References Cited UNITED STATES PATENTS 2,450,763 10/1948 McNalI 3 l 3/46X 3,141,987 7/1964 Altman 313/46X 3,193,003 7/1965 McCuen 313/46X 3,383,551 5/1968 Gerard 313/46X Primary Examiner-John Kominski Assistant Examiner-C. R. Campbell Attorney-Wenderoth, Lind & Ponack ABSTRACT: The magnetron device of the present invention comprises a magnetron tube, a heat conducting core surrounding the said magnetron tube, heat radiating fins fixed to the said heat conducting core, and a magnetic circuit device for operation of the magnetron tube. The heat radiation system of the present invention assures sufficient spontaneous heat radiation for a magnetron tube of high frequency output as large as 500 watts.

The shape of the core is so designed that the heat of the magnetron tube can be conducted through it to the fins evenly as well as efficiently.

PATENTEDBEMQ'IQYB 3.551.717

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2 33 YOSHIO KA'ro,

OSAMU KONOSU4 and 6| YOSHIO NAKAGAWA,

Inventor S B, QMMLXJ MA Attorney Intensity of magnet field (gauss) v Q "PATENTED nEczs I976 SHEET 2 [IF 2 YOSHIO NAKAGAWA I rwenlof s Cf v) Allorn'ey FINNED COOLER OFTIIE SOLID BLOCK TYPE FOR M AGNETRONS This invention relates to a magnetron device. More particularly, this inventionrelates to a spontaneously cooled type magnetron device capable of an oscillating high frequency output power as large as 500 watts.

Conventionally, the magnetron devices having a high frequency output power such as about 500 watts or a larger output power are generally operated with a forced cooling system utilizing, for instance, electric fan draught for cooling the outer surface of the tubular anode of the magnetron tube. Such a forced cooling system needs not only a complicated and bulky draught device as well as being uneconomical to run, but also makes annoying noise during its operation. There has also been known a conventional design of spontaneously cooled magnetron devices, but their utmost high frequency output power has been limited only to about 200 watts.

The object of the present invention is to provide a new and useful magnetron device of the spontaneously cooled type, capable of sufficiently radiating heat from the anodes of mag netron tubes as large as 500 watts high frequency power output.

Another object of the present invention is to provide a new and useful magnetron device of the spontaneously cooled type having an efficient magnetic circuit capable of supplying the magnetron tube with an intense magnetic field for operation.

There are other objects and particularities of the present invention, which will become apparent from the following detailed description and the accompanying drawings, in which:

FIG. 1 a is an elevation view of the magnetron device embodying the present invention;

FIG. 1 b is an elevational cross-sectional view taken at line b-b' in FIG. 2;

FIG. 2 is a plan view of the magnetron device shown in FIG. I a;

FIG. 3 is a plan view of the heat conducting core arranged in combination with a pair of permanent magnets arranged in relation to the said core; and

FIG. 4 is a graph showing the relation between the spacing of the permanent magnets and intensity of magnetic field at the center of the magnetron tube placed in a hole of the said core.

In the drawings FIG. 1 a, FIG. 1 b and FIG. 2, a tubular anode 2 of a magnetron tube 1 is inserted so as to fit tightly in a hole 4 at the center of a heat conducting core 3. The heat conducting core 3 consists of a metal block of nonmagnetic and heat-conductive material, for instance, aluminum or aluminum alloy, having its height approximately equal to that of the said tublar anode 2. A pair of cylindrical permanent magnets 5 and 5' are embraced in hollows 31 and 32; respectively, onthe front and rear side of the core 3 (see FIG. 3) as well as supported by lower yoke 6 and upper yoke 6', respectively, which are mixed to the lower and upper faces of the core 3 by bolts 7 and 7 The magnetic flux from the said permanent magnets 5 and 5' flows, through respective yokes 6-and 6', through the space between lower pole hole 61 of the yoke 6 and upper pole hole 6l of the yoke 6, thereby supplying the necessary magnetic field to the magnetron tube 1.

To the right and left sides of the core 3 are fixed respective trunks 81 and 81', of the heat radiating fins 8 and 8, both made of heat conducting material, for instance, aluminum or aluminum alloy, by means of bolts 33 and 34, respectively.

The heat conducting core 3 is shaped as shown in FIG. 3, so as to enable even and efficient conduction of heat from the tublar anode 2 ofthe magnetron tube 1 to the radiating fins 8 and 8, as well as to enable even distribution of the magnetic field in the magnetron tube 1 through the symmetrical arrangement of the permanent magnets 5 and 5. That is to say, the hollows 31 and 32 are arranged symmetrically with respect to the center of the magnetron tube 1, and are fonned by curved surfaces having asymptotic planes 91, 92 and 93, 94, respectively, which circumscribe the hole 4. The permanent magnets 5 and 5' are embraced in the hollows 31 and 32,

respectively, of the core 3, while right and left side surfaces of the core 3 are connected to fin trunks 81 and 81, respectively, with large connection faces. According to the above-mentioned structure of the core 3, the heat conduction in every direction in the core 3 is even as well as smooth, so that the temperature distribution at the connection face between the core 3 and the fin trunk 81, as well as that between the core 3 and the fin trunk 81', is sufficiently even. The heat conduction between the core 3 and fin trunks 81 as well as 81' is very smooth, too, on account of the large connection faces between them, and the heat conduction from the magnetron tube 1 through the core 3 to fins 8 and 8 is carried out with good efficiency. Moreover, according to the above-mentioned structure with the embracing arrangement of the magnets 5 and 5 in the symmetrically arranged hollows 31 and 32 of the core 3, an intense as well as even magnetic field can be obtained in the magnetron tube, as a result of the small distance L between the permanent magnets 5 and 5 and the symmetrical arrangement thereof. In addition, on account of the structure in which the heat conducting core and the heat radiating fins are made in separate metal blocks to form one heat radiating means, this magnetron device can be easily mass-produced.

Following are the dimensions of an example referred to in FIG. 3 of an aluminum heat conducting core and of magnets arranged with the core:

Diameter of the hole 4 mm D=48 Diameter of the magnets 5,5 "mmd=30 Depth at the center of the core 3 mrn L =70 Depth at the side faces of the core 3 -mm- L Distance between the respective centers of a pair of the magnets mm L 120 Width of the core mm M= 120 Height of the core mm 41 The experiments carried out for an example of the device comprising the core 3 connected with the fins 8 and 8' prove that the drop of temperature between the inner wall of the hole 4 and the side connection faces of the core respectively to be connected to the fins 8 and 8' should be less than 50 C. for obtaining even and stable heat radiation from the tubular anode 2 of the magnetron tube 1.

Further experiments prove that the intensity of magnetic field at the center of the magnetron tube changes in relation to the distance between the centers of a pair of the magnets 5 and 5 as shown in FIG. 4. The curve in FIG. 4 proves the intensity of the magnetic field at the center of the magnetron device of the example reaches as high as 1800 Gausses.

As is apparent from the embodiment hereinabove described, the present invention has provided a magnetron device comprising a heat conducting core and heat radiating fins connected to the said core. This heat conducting core is shaped to have hollow parts for embracing permanent magnets, and the said curved surfaces of the hollow parts have asymptotic planes circumscribing the said hole. Consequently, a large intensity of the magnetic field at the center of the magnetron tube, as well as even and stable heat radiation from the magnetron tube, can be obtained.

We claim:

1. A magnetron device comprising a magnetron tube, a magnetic circuit device for supplying a magnetic field to the magnetron tube for operation thereof, and a heat radiating means comprising a heat conducting core of nonmagnetic material having a hole therethrough having the magnetron tube inserted therethrough and tightly fitting therein, and heat radiating fins mechanically as well as thermally combined with the said heat conducting core; said heat radiating fins being positioned outside the said magnetic circuit device, and the said core having curved hollow surfaces the ends of which are in planes which are asymptotic to and circumscribe the said hole, and magnets for supplying the said magnetic circuit with magnetic flux positioned in the hollows defined by said surfaces.

3. A magnetron device as claimed in claim 1 wherein the heat conducting core and the heat radiating fins are separate metal blocks and are joined to form one heat radiating means. 

